ENERGY ANALYSIS AND CFD MODELLING OF DOWNDRAFT GASIFIER FOR BIOMASS GASIFICATION

Abstract

Biomass energy combined with computational fluid dynamics (CFD) software has been described in some detail in the following study. The aspect of biomass gasifier has been investigated with regard to the potential of designing future gasifier using simulation in FLUENT software. The project is about the study and CFD modeling of fluid flow of biomass fuel inside biomass downdraft gasifier. Gasifier is divided in to three different zones viz. 1.Drying and Pyrolysis Zone. 2.Oxidation Zone. 3.Reduction Zone. Firstly the study of gasification process is undertaken by means of thermodynamic equilibrium modeling in each zones with the help of EES software and the effect of moisture content on model is evaluated. Then using the typical design of gasifier, a 2-D model is produced for easier iterations and simulations. The type of gasifier modeled is atmospheric Downdraft gasifier. The gasifier model is set to have initial temperature at 400 K and operating pressure of 1 atmosphere. After iterating in FLUENT with first-order discretization, the results obtained are convergent and show that using second-order discretization is not suitable for 2-Dimensional model. Finally performance evaluation of gasification process is undertaken and future investigations are also suggested in this study for more accurate result using computational fluid dynamic (CFD) software.